JPH0713107Y2 - Tape cassette - Google Patents

Description

The present invention relates to a magnetic tape cassette, and more particularly to a magnetic tape cassette having an improved tape guide.

(Prior art and its problems) A magnetic tape cassette generally accommodates a pair of tape winding hubs in a case formed by a pair of upper and lower halves, winds the magnetic tape around them, and attaches this magnetic tape from one hub. It is adapted to be wound around the other hub through the front part of the case. Various guide rollers and fixed guide ribs are provided on the front part of the case to bring the magnetic tape into close contact with the magnetic head on the recorder side so that the magnetic tape can run uniformly. The present invention relates to an improvement of the fixed tape guide.

1 and 2 show a conventional fixed tape guide rib provided on the front part of the magnetic tape cassette. However, the upper and lower halves are omitted for convenience of explanation. In order to properly guide the magnetic tape, the recesses 1 and 2 aligned with the reference holes 12 and 13 which are conventionally formed in the upper and lower halves for position regulation with respect to the recorder.
A pair of guide ribs 3, 4 and 5, 6 projecting from both sides (see FIG. 5) toward the front of the cassette are formed. These ribs are parallel to the surface of the magnetic tape T and have a height larger than the magnetic tape width. These guide ribs 3, 4, 5, 6
The surface connecting the ridges (the straight front edge) is a plane that regulates the running path of the magnetic tape.

However, since the guide ribs are the end points of the resin flow during the plastic molding in which the molten resin is injected from the gate G, the resin does not often wrap around and bubbles are generated in the molded product, and gas escape is bad. In some cases, discoloration (reaction of monomers in the resin) occurred, resulting in poor appearance of the finished product, and dimensional accuracy not satisfying design requirements.

As another conventional example, as shown in FIGS. 3 to 4, annular bodies 7 and 8 are provided around the upper and lower ends of the reference holes 1 and 2, and these are integrally fixed to the guide ribs 3 and 4 or the ribs 5 and 6. There is something. The primary purpose of these annular bodies is to precisely finish them and the corresponding fitting holes in the upper and lower halves to serve as dimensional references for other parts and for the recorder. However, even in this conventional example, the front edges of the guide ribs 3, 4, 5 and 6 are the last places where the resin flows during molding, and since the resin has a relatively narrow width, the resin flow is not sufficient. As shown in FIG. 5, defects occur in the front edges 3, 4, 5, and 6 (the figure is exaggerated).

(Object of the Invention) Accordingly, it is an object of the present invention to provide a fixed tape guide rib in a magnetic tape cassette having the above-mentioned fixed tape guide rib in the front portion thereof, in which a defective shape and bubbles and discoloration do not occur.

Yet another object of the present invention is to provide a fixed tape guide rib which can simultaneously serve as a dimensional reference.

(Outline of Configuration and Effect of the Invention) The present invention accommodates a pair of tape winding hubs in a case formed by upper and lower halves, and the tape wound around the hubs passes through a fixed tape guide rib on the front of the case. In a tape cassette of a traveling type, the fixed tape guide ribs project toward the front of the case so as to define a guide path for the tape and also project to form a front edge wider than the width of the magnetic tape. A tape cassette is characterized in that the tape guide ribs are formed adjacent to each other, and the upper and lower ends of their protruding front edges are integrally connected to each other by bridging portions made of the same material. Preferably, the bridging portion is formed to have a constant width, and the bridging portion is projected in the vertical direction by a constant height, so that it can be used as a dimensional reference for the upper and lower halves.

According to the present invention, since the bridge portion provides escape for the resin, it is possible to provide a highly accurate fixed guide rib without bubbles or discoloration,
Further, the bridging portion can be used as a dimensional reference, and the dimensional accuracy can be improved as a whole.

(Example) Next, the Example of this invention is described in detail with reference to drawings.

FIG. 5 is an overall view of a magnetic tape cassette to which the present invention is applied, which includes upper and lower halves 10 and 11, a pair of rotatable magnetic tape winding hubs 14 and 15, and a front portion 16 having various guiding means. The tape T is adapted to run on the front portion 16 by a guide means.

Figures 6 to 9 show the front part without the upper and lower halves of the front part.
16 is an enlarged view of two pairs of tape guide ribs 3, 4 and 5 which project from both sides of the reference holes 12 and 13 to the same plane in front of the front main body 17 and terminate in a linear front edge as in the conventional case. , 6 are provided. These guide ribs are integrally formed with the main body 17 by plastic molding. Also,
In accordance with the present invention, the upper and lower bridges 1 with arched top surfaces
8, 18 and 19, 19 connect the upper and lower ends of the linear front edges of the pair of ribs 3, 4 and 5, 6 to each other. These bridging portions 18 and 19 have a constant width as much as possible, and by projecting vertically from the upper and lower surfaces of the main body 17 at a constant height, they serve as dimensional standards for the upper and lower halves. In this example, the outer surface of the bridge portion has an arcuate surface.

(Function and Effect) With the above configuration, during plastic injection molding,
The molten plastic injected from the gate G flows in the direction of the arrow and is completely injected into the guide ribs 3, 4, 5 and 6 due to the presence of the bridging portions 18 and 19 which act as escapes, and the final filling portion is in the bridging portion. And the weld line is the end point. For this reason, since the plastic can be uniformly solidified by the guide ribs, it is possible to provide a guide rib that is free from shape defects, bubbles and discoloration, and has high dimensional accuracy.

[Brief description of drawings]

FIG. 1 is a plan view of the conventional magnetic tape cassette without the upper and lower halves of the front portion, FIG. 2 is a perspective view of the II-II portion of FIG. 1, and FIG. 3 is another conventional cassette. A similar plan view of the front part, FIG. 4 is a front view taken along the line IV-IV of FIG. 3, FIG. 5 is a plan view of a magnetic tape cassette to which the present invention is applied, and FIG. 6 is a view of the present invention. FIG. 7 is a plan view of the front portion having fixed tape guide ribs excluding upper and lower halves, FIG. 7 is a front view thereof, FIGS. 8 and 9 are sectional views taken along lines AA and CC of FIG. 6, and FIG. It is a BB sectional view of FIG.

Claims (2)

[Scope of utility model registration request] 1. A tape cassette of a type in which a pair of tape winding hubs are housed in a case formed by upper and lower halves, and a tape wound around the hubs is made to run through a fixed tape guide rib on the front of the case. The fixed tape guide ribs project toward the front of the case so as to define the guide path of the tape and project wider than the width of the magnetic tape to form a front edge, and these fixed tape guide ribs are formed adjacent to each other. , A tape cassette characterized in that the upper and lower ends of the protruding front edges are integrally connected to each other by bridging portions made of the same material. 2. A tape cassette, characterized in that the bridging portions are formed to have a constant width, and the bridging portions are projected in the vertical direction by a constant height.